Prestack Depth Migration for Gas Hydrate Seismic Data of the East Sea

동해 가스 하이드레이트 탄성파자료의 중합전 심도 구조보정

  • Jang, Seong-Hyung (Korea Institute of Geoscience and Mineral Resources, Petroleum and Marine Resource) ;
  • Suh, Sang-Yong (Korea Institute of Geoscience and Mineral Resources, Petroleum and Marine Resource) ;
  • Go, Gin-Seok (Chosun University, Resource Engineering)
  • 장성형 (한국지질자원연구원 석유해저자원연구부) ;
  • 서상용 (한국지질자원연구원 석유해저자원연구부) ;
  • 고진석 (조선대학교 자원공학과)
  • Published : 2006.12.30

Abstract

In order to study gas hydrate, potential future energy resources, Korea Institute of Geoscience and Mineral Resources has conducted seismic reflection survey in the East Sea since 1997. one of evidence for presence of gas hydrate in seismic reflection data is a bottom simulating reflector (BSR). The BSR occurs at the interface between overlaying higher velocity, hydrate-bearing sediment and underlying lower velocity, free gas-bearing sediment. That is often characterized by large reflection coefficient and reflection polarity reverse to that of seafloor reflection. In order to apply depth migration to seismic reflection data. we need high performance computers and a parallelizing technique because of huge data volume and computation. Phase shift plus interpolation (PSPI) is a useful method for migration due to less computing time and computational efficiency. PSPI is intrinsically parallelizing characteristic in the frequency domain. We conducted conventional data processing for the gas hydrate data of the Ease Sea and then applied prestack depth migration using message-passing-interface PSPI (MPI_PSPI) that was parallelized by MPI local-area-multi-computer (MPI_LAM). Velocity model was made using the stack velocities after we had picked horizons on the stack image with in-house processing tool, Geobit. We could find the BSRs on the migrated stack section were about at SP 3555-4162 and two way travel time around 2,950 ms in time domain. In depth domain such BSRs appear at 6-17 km distance and 2.1 km depth from the seafloor. Since energy concentrated subsurface was well imaged we have to choose acquisition parameters suited for transmitting seismic energy to target area.

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